PENGENDALIAN TANAMAN AIR Hydrilla verticillata (HYDRILLA) DAN Eichhornia crassipes (ENCENG GONDOK) SECARA BIOLOGIS DI PERAIRAN UMUM

Abstract

The study of grass carp (Ctenopharyngodon
idella) as an aquatic weed control was conducted
in the Fish Breeding Centre Board at
Umbulan, Pasuruan. The objectives of the study
was to find out: (1) The effective grass carp size
for controlling water hyacinth in pond waters;
(2) The effective depth of open waters in which
the grass carp controlling hydrilla; (3) The
effective size of grass carp controlling water
hyacinths in open waters. The results showed
that the water hyacinth fed effectively by the
grass carp of 125 g each, the highest fed in the
fourth week. However, the highest growth rate
was in the second week. The fish size influence
the growth rate and the amount of waterhyacinth
fed during the study. The most effective depth
of open waters which was suitable for fish to
control hydrilla was 1 m. The amount of
hydrilla fed was till six times of its weight. The
smaller fish was faster in growth than the bigger
one. The amount of water hyacinth fed by grass
carp was larger than hydrilla. The percentage of
the aquatic weeds consumed by big fish was
smaller than the small fish, although the total
weight was in larger amount.